yo Peter,
There’s a music university in Chengdu which is the gathering point for many of the music shops in the city. You can get guitars, pianos, traditional Chinese instruments etc there and prices are pretty reasonable. I spent 700 yuan on an Epiphone dreadnought acoustic which is comparable to what you’d get in the states for about $100 – perfectly fine for me since I’m not a guitar wizard or anything.
Musicians hang out in People’s Park, but those are mostly traditional Chinese instruments and… old.. people. Jia Bar has jams all the time though, they have a drum kit and electric guitars and bass.
Welcome to Chengdu and to the site-